With the objective of suppressing resist pattern collapse generated at dry etching, energy rays are applied to a photoresist structure including an antireflection film provided on a base and a resist pattern brought into contact with the antireflection film, the resist pattern being a chemical-amplification photoresist provided on the antireflection film. Thereafter, the photoresist structure is heated at a heating temperature greater than or equal to a glass transition point of the resist pattern and less than a melting point thereof.